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User Contributed Notes 2 notes

Note that DOMDocumentFragment is a bit special when it's added to another node. When that happens, not the fragment itself is added as a child, but all of the children of the fragment are moved over to the new parent node.

For example, consider this script:

<?php

/* Create a document and a fragment containing a single node */$doc = new DOMDocument();$fragment = $doc->createDocumentFragment();$fragment->appendChild($doc->createElement('foo'));

/* Now, the foo node is a child of the fragment */var_dump($fragment->firstChild);

/* After appending the fragment to another node, the children of the * fragment will have been transfered to that node (and the fragment is * not present in the children list!) */$doc->appendChild($fragment);/* So the fragment has no children anymore */var_dump($fragment->firstChild);/* But $doc has a single child, which is the foo element, not the * fragment */var_dump($doc->childNodes->length);var_dump($doc->firstChild);

...will fail on step 3 with a "read only" error as $docFrag is not created as a child of DOMDocument.

I'm not sure of the reason for this: on the web people have cited security, and others have cited poor design however whatever the reason, it is really limiting when wanting to encapsulating generic independent DocumentFragments into classes for easy grafting to the desired tree. The only workarounds i have seen look expensive from a performance perspective and cumbersome from a coding perspective ie. create a dummy $dom for temporary use.

(This is valid as of PHP 5.3) I've put this here as i've wasted a lot of time finding it out - I hope this saves others some heartache.